This invention relates to a vacuum cleaner having primary and secondary filters, and more specifically, to an improved filter assembly for use as a secondary filter.
Vacuum cleaners operate by filtering dirty air that flows through a main housing between a vacuum cleaner inlet and outlet. One well-known type of vacuum cleaner uses a primary filter that incorporates a basin filled with liquid, preferably water. A separator driven by a motor separates the dirt particles from the air and deposits them into the water. Although such filter arrangements can be highly effective, inevitably the vacuum cleaner filter is unable to filter all the air and smaller particles of dirt escape through the outlet. To address this problem, a secondary filter has been incorporated to further filter the air. The secondary filter is arranged between the primary filter and the outlet to trap very small dirt particles. A pleated fibrous filter, such as a HEPA filter, has been used that permits only virtually dirt-free air to be expelled from the vacuum cleaner outlet.
It is difficult to provide the vacuum cleaner user convenient access to the secondary filter located within the main housing when changing the filter. Several components have been used as part of the filter assembly, and may be eliminated to reduce cost. The filter has not been located within the housing in such a manner that ensures proper placement and easy replacement of the filter. Furthermore, when the user replaces the filter one is confronted with a dirty filter that is messy and undesirable in appearance. Therefore, what is needed is a self-contained filter assembly having fewer components that is self-locating for easy replacement.
The present invention provides a filter assembly for a vacuum cleaner that includes a main housing having an inlet and an outlet. A motor moves air from the inlet to the outlet, and a first filter is arranged between the inlet and the outlet for filtering the air. An inner wall and an outer wall that is spaced apart from the inner wall form a cavity between the walls. The cavity is located between the first filter and the outlet. The inner wall has an inner opening that permits air to flow from the first filter into the cavity, and the outer wall has an outer opening. A back cover is removably secured to the outer wall over the outer opening to seal the cavity and guide the air from the cavity to the outlet. The back cover includes an access opening that is removably secured to the back cover over the access opening to seal the access opening. A filter cartridge is removably disposed within the cavity. The filter cartridge has a first side with a first opening and a second side opposite the first side and adjacent to the access cover with a second opening. The filter cartridge has a second filter disposed therein between the first and the second openings for further filtering the air. A portion of the first side is in sealing engagement with a portion of the inner wall such that the first opening is aligned with the inner opening wherein the motor moves the air from the inner opening to the second opening.
Accordingly, the above filter assembly provides a self-contained filter assembly having fewer components that is self-locating for easy replacement.